I found this article from the Independent Security Evaluators (ISE).
In short, they were able to extract the master password, secret key and individual items and respective passwords from memory. It was done either when 1Password was in an unlocked state or locked state. The only way to clear memory was to exit out of the application totally.
It doesn't say how the sync was made (families, teams, dropbox, etc.) but I don't think it matters as what they had done was in the memory of the host machine.
If this is true, will it be fixed in future updates? Also, is this something present in other operating systems (MacOS, OS X, iOS,
1Password Version: 7.2.576
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Not Provided